Cutting elements comprising sensors, earth-boring tools comprising such cutting elements, and methods of forming wellbores with such tools

ABSTRACT

An earth-boring tool includes a cutting element comprising a hard material and at least one of a signal generator configured to provide an electromagnetic or acoustic signal to an interface between a surface of the hard material and a surface of a subterranean formation, and a sensor configured to receive an electromagnetic or acoustic signal from the interface. A method of forming a wellbore includes rotating the earth-boring tool within a wellbore and cutting formation material with a cutting element, transmitting a signal through the cutting element to an interface between the cutting element and the formation material, and measuring a response received at a sensor. A cutting element includes a transmitter oriented and configured to dispense a signal to an interface between the cutting surface and a surface of a formation and a sensor oriented and configured to measure a signal from the interface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/219,886, filed Mar. 19, 2014, now U.S. Pat. No. 9,995,088, issuedJun. 12, 2018, which application claims the benefit of the filing dateof the U.S. Provisional Patent Application No. 61/819,720, filed May 6,2013, the disclosure of each of which is hereby incorporated herein itits entirety by this reference.

FIELD

Embodiments of the present disclosure generally relate to drill bits andcutting elements that include a signal generator and/or a sensor, and tomethods of forming and using such drill bits and cutting elements.

BACKGROUND

Earth-boring tools are commonly used for forming (e.g., drilling andreaming) bore holes or wells (hereinafter “wellbores”) in earthformations. Earth-boring tools include, for example, rotary drill bits,core bits, eccentric bits, bi-center bits, reamers, underreamers, andmills.

Different types of earth-boring rotary drill bits are known in the artincluding, for example, fixed-cutter bits (which are often referred toin the art as “drag” bits), roller cone bits (which are often referredto in the art as “rock” bits), diamond-impregnated bits, and hybrid bits(which may include, for example, both fixed cutters and roller cones).The drill bit is rotated and advanced into the subterranean formation.As the drill bit rotates, the cutters or abrasive structures thereofcut, crush, shear, and/or abrade away the formation material to form thewellbore.

The drill bit is coupled, either directly or indirectly, to an end ofwhat is referred to in the art as a “drill string,” which comprises aseries of elongated tubular segments connected end-to-end that extendsinto the wellbore from the surface of the formation. Often various toolsand components, including the drill bit, may be coupled together at thedistal end of the drill string at the bottom of the wellbore beingdrilled. This assembly of tools and components is referred to in the artas a “bottom-hole assembly” (BHA).

The drill bit may be rotated within the wellbore by rotating the drillstring from the surface of the formation, or the drill bit may berotated by coupling the drill bit to a downhole motor, which is alsocoupled to the drill string and disposed proximate the bottom of thewellbore. The downhole motor may comprise, for example, a hydraulicMoineau-type motor having a shaft, to which the drill bit is mounted,that may be caused to rotate by pumping fluid (e.g., drilling mud orfluid) from the surface of the formation down through the center of thedrill string, through the hydraulic motor, out from nozzles in the drillbit, and back up to the surface of the formation through the annularspace between the outer surface of the drill string and the exposedsurface of the formation within the wellbore.

The cutting elements used in earth-boring tools often includepolycrystalline diamond cutters (often referred to as “PDCs”), which arecutting elements that include a polycrystalline diamond (PCD) material.Such polycrystalline diamond-cutting elements may be formed by sinteringand bonding together relatively small diamond grains or crystals underconditions of high temperature and high pressure in the presence of acatalyst (such as cobalt, iron, nickel, or alloys and mixtures thereof)to form a layer of polycrystalline diamond material on a cutting elementsubstrate. These processes are often referred to as hightemperature/high pressure (or “HTHP”) processes. The cutting elementsubstrate may include a cermet material (i.e., a ceramic-metal compositematerial) such as cobalt-cemented tungsten carbide. In such instances,the cobalt (or other catalyst material) in the cutting element substratemay be drawn into the diamond grains or crystals during sintering andserve as a catalyst material for forming a diamond table from thediamond grains or crystals. In other methods, powdered catalyst materialmay be mixed with the diamond grains or crystals prior to sintering thegrains or crystals together in an HTHP process.

The oil and gas industry expends sizable sums to design cutting tools,such as downhole drill bits including roller cone rock bits andfixed-cutter bits. Such drill bits may have relatively long servicelives with relatively infrequent failure. In particular, considerablesums are expended to design and manufacture roller cone rock bits andfixed-cutter bits in a manner that minimizes the probability ofcatastrophic drill bit failure during drilling operations. The loss of aroller cone or a polycrystalline diamond compact from a bit duringdrilling operations can impede the drilling operations and, at worst,necessitate rather expensive fishing operations.

Diagnostic information related to a drill bit and certain components ofthe drill bit may be linked to the durability, performance, and thepotential failure of the drill bit. In addition, characteristicinformation regarding the rock formation may be used to estimateperformance and other features related to drilling operations. Loggingwhile drilling (LWD), measuring while drilling (MWD), and front-endmeasurement device (FEMD) measurements are conventionally obtained frommeasurements behind the drill head, such as at several feet away fromthe cutting interface.

BRIEF SUMMARY

In some embodiments, an earth-boring tool includes at least one cuttingelement comprising a hard material and at least one of a signalgenerator configured to provide an electromagnetic or acoustic signal toan interface between a surface of the hard material and a subterraneanformation in contact with at least a portion of the surface, and asensor configured to receive a return electromagnetic or acoustic signalfrom the interface.

A method of forming a wellbore includes rotating an earth-boring toolwithin a wellbore and cutting formation material with at least onecutting element mounted thereto, transmitting a signal through at leastone cutting element to an interface between a surface of the at leastone cutting element and the formation material, and measuring a responsereceived at a sensor from the interface as the at least one cuttingelement is used to cut formation material. The at least one cuttingelement comprises a generally planar volume of hard material. Theearth-boring tool further comprises a transmitter coupled to the atleast one cutting element, the transmitter comprising at least one of anelectromagnetic and an acoustic transmitter, and a sensor coupled to theat least one cutting element. The sensor is at least one of aspectrometer and an acoustic receiver, the signal is at least one of anelectromagnetic signal and an acoustic signal, and the response is atleast one of an electromagnetic and an acoustic response.

In some embodiments, a cutting element for an earth-boring drilling toolincludes a cutting element body having a cutting surface thereon, atleast one transmitter oriented and configured to dispense anelectromagnetic or acoustic signal to an interface between the cuttingsurface and a surface of a subterranean formation engaged by at least aportion of the cutting surface, and at least one sensor oriented andconfigured to measure a signal returned from the interface between thecutting surface and the surface of the subterranean formation engaged bythe at least a portion of the cutting surface.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming embodiments of the present invention, advantagesof embodiments of the disclosure may be more readily ascertained fromthe description of certain example embodiments set forth below, whenread in conjunction with the accompanying drawings, in which:

FIG. 1 is a partial cross-sectional view of an embodiment of anearth-boring drill bit;

FIGS. 2 through 4 are partial cross-sectional views of cutting elementshaving sensors;

FIG. 5 is a simplified schematic of the cutting element of FIG. 4 incontact with a formation; and

FIG. 6 is a simplified chart illustrating acoustic signals transmittedthrough the cutting element of FIG. 4.

DETAILED DESCRIPTION

The illustrations presented herein are not meant to be actual views ofany particular cutting element, earth-boring tool, or portion of such acutting element or tool, but are merely idealized representations thatare employed to describe embodiments of the present disclosure.Additionally, elements common between figures may retain the samenumerical designation.

In this description, specific implementations are shown and describedonly as examples and should not be construed as the only way toimplement the present invention unless specified otherwise herein. Itwill be readily apparent to one of ordinary skill in the art that thevarious embodiments of the present disclosure may be practiced in otherarrangements or combinations.

Referring in general to the following description and accompanyingdrawings, various embodiments of the present disclosure are illustrated.Common elements of the illustrated embodiments may be designated withsimilar reference numerals. It should be understood that the figurespresented are not meant to be illustrative of actual views of anyparticular portion of the actual structure or method, but are merelyidealized representations employed to more clearly and fully depict thepresent invention defined by the claims below. The illustrated figuresmay not be drawn to scale.

As used herein, the term “earth-boring tool” means and includes any typeof bit or tool used for drilling during the formation or enlargement ofa wellbore in subterranean formations and includes, for example,fixed-cutter bits, rotary drill bits, percussion bits, core bits,eccentric bits, bi-center bits, reamers, mills, drag bits, roller conebits, hybrid bits and other drilling bits and tools known in the art.

As used herein, the term “polycrystalline material” means and includesany material comprising a plurality of grains or crystals of thematerial that are bonded directly together by inter-granular bonds. Thecrystal structures of the individual grains of the material may berandomly oriented in space within the polycrystalline material.

As used herein, the term “hard material” means and includes any materialhaving a Knoop hardness value of about 3,000 Kg_(f)/mm² (29,420 MPa) ormore. Hard materials include, for example, diamond and cubic boronnitride.

FIG. 1 is a partial cross-sectional view of an earth-boring drill bit100, which may be employed in embodiments of the present disclosure. Theearth-boring drill bit 100 includes a bit body 110, which may be formedfrom steel. In some embodiments, the bit body 110 may be formed from aparticle-matrix composite material. For example, the bit body 110 mayfurther include a crown 114 and a steel blank 116. The steel blank 116is partially embedded in the crown 114. The crown 114 may include aparticle-matrix composite material, such as particles of tungstencarbide embedded in a copper alloy matrix material. The bit body 110 maybe secured to a shank 120 by way of a threaded connection 122 and a weld124 extending around the earth-boring drill bit 100 on an exteriorsurface thereof, along an interface between the bit body 110 and theshank 120. Other methods may be used to secure the bit body 110 to theshank 120.

The earth-boring drill bit 100 may include a plurality of cuttingelements 154 attached to a face 112 of the bit body 110. Generally, thecutting elements 154 of a fixed-cutter type drill bit have either a diskshape or a substantially cylindrical shape. A cutting element 154includes a cutting surface 155 located on a substantially circular endsurface of the cutting element 154. The cutting surface 155 may beformed by disposing a hard, superabrasive material, such as mutuallybound particles of polycrystalline diamond formed into a “diamond table”under high pressure, high temperature (HPHT) conditions, on a supportingsubstrate. The diamond table may be formed onto the substrate during theHPHT process, or may be bonded to the substrate thereafter. Such cuttingelements 154 are often referred to as a polycrystalline compact or apolycrystalline diamond compact (PDC) cutting element 154. The cuttingelements 154 may be provided along blades 150, and within pockets 156formed in the face 112 of the bit body 110, and may be supported frombehind by buttresses 158, which may be integrally formed with the crown114 of the bit body 110. Cutting elements 154 may be fabricatedseparately from the bit body 110 and secured within the pockets 156formed in the outer surface of the bit body 110. If the cutting elements154 are formed separately from the bit body 110, a bonding material(e.g., adhesive, braze alloy, etc.) may be used to secure the cuttingelements 154 to the bit body 110. The earth-boring drill bit 100 mayalso include one or more cutting elements 160, 160′, 160″ instrumentedwith a sensor, as shown in FIGS. 2 through 4 and described in moredetail below.

The bit body 110 may further include junk slots 152 separating theblades 150. Internal fluid passageways (not shown) extend between theface 112 of the bit body 110 and a longitudinal bore 140, which extendsthrough the shank 120 and partially through the bit body 110. Nozzleinserts (not shown) also may be provided at the face 112 of the bit body110 in fluid communication with the internal fluid passageways.

The earth-boring drill bit 100 may be secured to the end of a drillstring, which may include tubular pipe and equipment segments (e.g.,drill collars, a motor, a steering tool, stabilizers, etc.) coupledend-to-end between the earth-boring drill bit 100 and other drillingequipment at the surface of the formation to be drilled. As one example,the earth-boring drill bit 100 may be secured to the drill string withthe bit body 110 being secured to the shank 120 having a threadedconnection 125 and engaging with a threaded connection of the drillstring. An example of such a threaded connection portion is an AmericanPetroleum Institute (API) threaded connection.

During drilling operations, the earth-boring drill bit 100 is positionedat the bottom of a borehole such that the cutting elements 154 areadjacent the subterranean formation to be drilled. Equipment such as arotary table or a top drive may be used for rotating the drill stringand the drill bit 100 within the borehole. Alternatively, the shank 120of the earth-boring drill bit 100 may be coupled directly to the driveshaft of a down-hole motor, which may be used to rotate the earth-boringdrill bit 100. As the earth-boring drill bit 100 is rotated, drillingfluid is pumped to the face 112 of the bit body 110 through thelongitudinal bore 140 and the internal fluid passageways. Rotation ofthe earth-boring drill bit 100 causes the cutting elements 154 to scrapeacross and shear away the surface of the subterranean formation. Theformation cuttings mix with, and are suspended within, the drillingfluid and pass through the junk slots 152 and the annular space betweenthe well bore hole and the drill string to the surface of the earthformation.

FIG. 2 is a partial cross-sectional view of a cutting element 160instrumented with a sensor. The cutting element 160 includes a diamondtable 162 over a substrate 164, and includes a cutting surface 155 onthe diamond table 162. The cutting element 160 includes a signalgenerator 166 and a sensor 168, which may be disposed within a void 170within or defined by the substrate 164. Although the void 170 is shownnear the center of the cutting element 160 for clarity of theillustration, the void 170 may be located anywhere in the cuttingelement 160. For example, the void 170 may be located adjacent aradially outward surface of the cutting element 160 or near a surface ofthe cutting element 160 in contact with the formation during drilling.The signal generator 166 is configured to provide a signal to aninterface between the diamond table 162 and a subterranean formationwhen the cutting element 160 is in use. The sensor 168 is configured toreceive a signal from the interface between the diamond table 162 andthe subterranean formation when the cutting element 160 is in use. Insome embodiments, the signal generator 166 and the sensor 168 maytogether be a single transceiver 167. In other embodiments, the signalgenerator 166 and the sensor 168 may be distinct devices, and may bedisposed on or within the same cutting element 160 or on differentcutting elements 160. After a first well is drilled in a field (whichmay be referred to in the art as a “wildcat well”), information aboutthe layers of geologic formations of the earth (which may have differentmineralogies) of the first well may be used to estimate an expecteddepth of those layers for subsequently drilled wells (which may bereferred to in the art as “development wells”). Determining mineralogyat the bit in real-time may allow an operator to correlate the currentbit location in terms of the geologic formations that had been drilledpreviously in nearby (or “offset”) wells. Real-time mineralogy at thebit can also aid in geosteering and in knowing when a well is entering aformation known to be geopressured, based on experience with earlieroffset wells.

In some embodiments, the transceiver 167 may be a spectrometer. Forexample, the transceiver 167 may be an infrared spectrometer, such as amid-infrared spectrometer. The transceiver 167 may be configured toprovide and detect electromagnetic radiation having wavelengths fromabout 2.5 μm to about 25.0 μm, such as from about 2.5 μm to about 12.0μm. The transceiver 167 may be used to study fundamental vibrations andassociated rotational-vibrational structures of the subterraneanformation. The electromagnetic radiation provided by the signalgenerator 166 may penetrate a relatively short distance into thesubterranean formation, such as from about 5.0 μm to about 75.0 μm fromthe surface (e.g., from about 2 to about 3 wavelengths of theradiation). Thus, the electromagnetic radiation may be used to measureproperties of solid material at or near the surface of the materialbeing cut, and may provide information about the composition of thematerial in real-time or near real-time. Infrared spectrometers mayinclude pyroelectric infrared detectors (e.g., a single pyroelectricdetector or an array of pyroelectric detectors). For example,pyroelectric infrared spectral detectors are available from InfraTecGmbH, of Dresden, Germany, from Pyreos Ltd. of Edinburgh, Scotland, UK,and from IR Microsystems, of Lausanne, Switzerland. Such spectraldetectors may fit within the space occupied by conventional cuttingelements, and may be coupled with an infrared source.

In some embodiments, the infrared source may include a hot filament(e.g., a filament maintained at about 950° C.); a steady-state infraredemitter (e.g., as available from Helioworks, Inc., of Santa Rosa,Calif.) in combination with a mechanical or other beam chopper; amicro-machined, electrically-modulated, thermal infrared emitter (e.g.,as available from Leister Process Technologies LLC, of Itasca, Ill.under the trade name AXETRIS®), an infrared light-emitting diode (e.g.,as available from LED Microsensor NT, LLC, of Saint Petersburg, Russia),a superluminescent light-emitting diode (e.g., as available fromDenseLight Semiconductor, of Singapore), a laser diode (e.g., asavailable from nanoplus GmbH, of Gerbrunn, Germany), or a supercontinuumfiber laser (e.g., as available from Omni Sciences, Inc., of Dexter,Mich.).

The infrared source may be, for example, a modulated or pulsed source.The small size of spectral detectors means that their components havesmall mass (m) so, under high accelerations (a) associated with theshock and vibration of a drill bit, they experience correspondinglysmall forces (F) because F=ma. The transceiver 167 may include amicroprocessor configured to calculate one or more properties of thesubterranean formation. For example, the transceiver 167 may include asource, detector, and/or microprocessor as described in U.S. Pat. No.7,423,258, issued Sep. 9, 2008, and titled “Method and Apparatus forAnalyzing a Downhole Fluid Using a Thermal Detector,” the disclosure ofwhich is incorporated herein in its entirety by this reference.

In some embodiments, the transceiver 167 may be a Raman spectrometer.The transceiver 167 may be configured to emit and detect electromagneticradiation having wavelengths from about 200 nm to about 1500 nm, such asfrom about 250 nm to about 100 nm. The transceiver 167 may be used tostudy vibrational, rotational, and other low-frequency modes of thematerial of the subterranean formation. The electromagnetic radiationmay irradiate the material of the subterranean formation, and the sensor168 may be configured to detect photons of energy shifted from thewavelength provided by the signal generator 166. Thus, theelectromagnetic radiation may be used to measure properties of solidmaterial at or near the surface of the material being cut, and maygather information about the composition of the material in real-time ornear real-time. Such information also may be transmitted to the surfaceof the formation for analysis in real-time or near real-time. Inaddition or as an alternative, the information acquired may be stored inmemory within the cutting element, the drill bit, or the bottom-holeassembly for analysis subsequent to the drilling operation afterremoving the bottom-hole assembly from the wellbore.

Electromagnetic radiation transmitted from the signal generator 166 andreceived by the sensor 168 may pass through the diamond table 162. Insome embodiments, the cutting element 160 may include a window 172through which the radiation may be transmitted and received. The window172 may be any material transparent to a wavelength of radiationtransmitted from the signal generator 166 and received by the sensor168. Some materials transparent to various wavelengths of radiation thatmay be used as windows 172 include AgBr, AgCl, Al₂O₃ (sapphire), GeAsSeglass, BaF₂, CaF₂, CdTe, AsSeTe chalcogenide glass, CsI, diamond, GaAs,Ge, KBr, TlBrI, LiF, MgF₂, NaCl, high-density polyethylene, borosilicateglass, Si, SiO₂ (quartz), ZnS, or ZnSe. Because the cutting element 160may be subjected to harsh downhole conditions of high pressure, hightemperature, and immersion in hot, aqueous or corrosive fluids, some ofthese materials may not have suitable chemical resistance or mechanicalstrength for use in cutting elements 160. The material of the window 172may be selected for its ability to withstand drilling conditions. Forexample, the window 172 may be a single-crystal diamond. Diamondtransmits electromagnetic radiation well in the range from about 0.25 μmto about 50.0 μm, so it may be particularly suited for transmission ofmid-infrared radiation. Furthermore, diamond has properties that make itamenable for use in drilling environments (e.g., chemical inertness,strength, etc.). The window 172 may be selected to have dimensions toaccommodate the signal generator 166 and the sensor 168. For example,the window 172 may be disc-shaped with a diameter of about 0.25 inch(about 6 mm) or less, about 0.125 inch (about 3 mm) or less, or evenabout 0.04 inch (about 1 mm) or less. The window 172 may have athickness approximately the same as a thickness of the diamond table162. In other embodiments, the window 172 may have a thickness greaterthan or less than the thickness of the diamond table 162. The window 172may be secured within the diamond table 162 and/or the substrate 164 by,for example, interbonding during an HPHT process, bonding with anadhesive, etc. In some embodiments, the window 172 may be or includeanother material transparent to a wavelength provided by the signalgenerator 166. For example, the window 172 may include silicon carbideor metallic silicon.

In certain embodiments, the radiation may be transmitted through thediamond table 162 itself, such as from one diamond particle to anotherbetween diamond-to-diamond contacts. In such embodiments, the diamondtable 162 may be formed in such a manner as to increase the number orsize of diamond-to-diamond contacts. For example the diamond table 162may be formed as described in U.S. patent application Ser. No.13/839,589, filed Mar. 15, 2013, and titled “Polycrystalline DiamondCompacts Including Diamond Nanoparticles, Cutting Elements andEarth-Boring Tools Including Such Compacts, and Methods of FormingSame;” U.S. patent application Ser. No. 13/782,341, filed Mar. 1, 2013,and titled “Methods of Fabricating Polycrystalline Diamond byFunctionalizing Diamond Nanoparticles, Green Bodies IncludingFunctionalized Diamond Nanoparticles, and Methods of FormingPolycrystalline Diamond Cutting Elements;” U.S. Patent ApplicationPublication No. 2013/0068540, published Mar. 21, 2013, titled “Methodsof Fabricating Polycrystalline Diamond, and Cutting Elements andEarth-Boring Tools Comprising Polycrystalline Diamond;” or U.S. PatentApplication Publication No. 2013/0068541, published Mar. 21, 2013,titled “Methods of Fabricating Polycrystalline Diamond, and CuttingElements and Earth-Boring Tools Comprising Polycrystalline Diamond.” Theentire disclosures of each of these applications and publications areincorporated herein by this reference.

In some embodiments, and as shown in FIG. 3, the radiation may betransmitted through one or more diamond fibers 174 that terminate at theedge of a cutting element 160′. In some embodiments, such fibers 174 maybe or comprise optical fibers configured to convey electromagneticradiation therethrough along the length of the fibers 174. The diamondfibers 174 may be formed as described in P. W. May et al., “Preparationof Solid and Hollow Diamond Fibres and the Potential for Diamond FibreMetal Matrix Composites, 13 J. MATERIALS SCIENCE LEITERS 247-249 (1994);and P. W. May et al., “Preparation of CVD Diamond Wires, Fibres, andTubes,” PROC. 3RD INT. SYMP. DIAMOND MATERS., HONOLULU, May 1993, pp.1036-1041. The entire disclosures of each of these publications areincorporated herein by this reference. The diamond fibers 174 may besecured within the diamond table 162 and/or the substrate 164 by, forexample, interbonding during an HPHT process, bonding with an adhesive,etc.

The transceiver 167 (or the signal generator 166 and the sensor 168) maybe connected to one or more electrical contacts 176. The electricalcontacts 176 are depicted in FIGS. 2 and 3 as wires, but may alsoinclude pins, posts, terminals, blades, etc. The electrical contacts 176may be connected to a data collection system and/or a controller. Forexample, a computer may serve as both a data collection system and acontroller. The electrical contacts 176 may be configured to transferelectrical power and/or data. The electrical contacts 176 may bedisposed within the bit body 110 (FIG. 1) and may transfer power and/ordata along the drill string.

In some embodiments, the transceiver 167 may be an acoustic transceiver180, as shown in the cutting element 160″ of FIG. 4. The acoustictransceiver 180 may be configured to vibrate the cutting element 160″ togenerate acoustic waves that travel through the diamond table 162 and/orthe substrate 164 to the subterranean formation. A portion of theacoustic waves may be reflected back to the acoustic transceiver 180,and some properties of the formation may be determined by comparing thereflected signal with the transmitted signal, as described in moredetail below. The acoustic transceiver 180 may provide and detectvibrations having frequencies from the low audible (15 Hz) to the highultrasonic (1 GHz), such as in the ultrasonic range of about 50 KHz toabout 100 MHz. Acoustic waves transmitted from the acoustic transceiver180 may pass through the diamond table 162 and/or the substrate 164 toan interface between the diamond table 162 and the formation. Theacoustic transceiver 180 may be used to study the difference between thecharacteristic impedance of the formation and the cutting element 160″.A material's acoustic impedance is its density times its sound speed.The acoustic reflection intensity at an interface between a cutter andan earth formation depends upon the acoustic impedance of the cutter andthe acoustic impedance of the earth formation. Thus, the earthformation's impedance can be calculated from the cutter's impedance andthe measured reflection intensity at the interface of the cutter withthat formation. The formation's impedance can be used to infer theformation's mineralogy if the pressure and temperature of the formationare known. The cutter's thickness can be determined from the cutter'ssound speed and the acoustic travel time within the cutter, which wouldsimultaneously allow cutter wear to be monitored in real-time or nearreal-time. The differences in characteristic impedances may provideinformation about the composition of the material in real-time or nearreal-time because each mineralogy has its own profile for acousticimpedance as a function of pressure and temperature and because pressureand temperature may also be measured at an earth-boring drill bit 100.

The earth-boring drill bit 100 (FIG. 1) may include various cuttingelements, including cutting elements 154 without any instrumentation andcutting elements 160, 160′, 160″ comprising signal generators 166 and/orsensors 168. In some embodiments, the earth-boring drill bit 100 mayinclude multiple instrumented cutting elements 160, 160′, 160″, whichmay be configured to measure different properties and/or locations alongthe path of the cutting elements 160, 160′, 160″. For example, somecutting elements 160, 160′ may be configured to measure infraredsignals, others may be configured to measure Raman shifts, and somecutting elements 160″ may be configured to measure acoustic responses.The cutting elements 160, 160′, 160″ may provide real-time or nearreal-time information about the properties of the minerals of theformation.

Wellbores may be formed by using cutting elements 160, 160′, 160″ shownin FIGS. 2 through 4. For example, the earth-boring drill bit 100(FIG. 1) may be attached to a drill string, which may be rotated whiledrilling. While drilling, a signal may be transmitted through thecutting element 160, 160′, 160″ to an interface between the cuttingelement 160, 160′, 160″ and the formation material. A response receivedat the sensor is measured as the cutting element is used to cutformation material. The response may be in the form of an infraredsignal, a Raman shift, an acoustic signal, or any other appropriatesignal.

For example, infrared spectroscopy may be used to help identify mineralsin a wellbore. Spectroscopy is described in, for example, R. N. Clark,“Spectroscopy of Rocks and Minerals, and Principles of Spectroscopy,” inMANUAL OF REMOTE SENSING, VOLUME 3, REMOTE SENSING FOR THE EARTHSCIENCES, 3-58 (A. N. Rencz, ed., 1999), the entire contents of whichare hereby incorporated by reference. Infrared spectra of mixtures ofwater and oil at various temperatures are described in J. Pironon etal., “Water in Petroleum Inclusions: Evidence from Raman and FT-IRMeasurements, PVT Consequences,” 69-70 Journal of GeochemicalExploration 663-668 (June 2000), the entire contents of which are herebyincorporated by reference. The spectra of water and oil vary withtemperature, pressure, and composition. Similar spectra can be generatedfor other materials encountered in forming wellbores, such as forhydrocarbons. Peaks appear at different wavenumbers depending on thematerial. Therefore, a material may be differentiated from othermaterials by its infrared spectrum. When drilling multiple wells in afield, the types of minerals in the field may be identified inearlier-drilled wells, such that in subsequent drilling operations, anoperator or a computer may identify the same minerals. Thus, drillingconditions may be varied in response to the in-situ identification ofminerals.

Different wavelengths (reciprocal wavenumbers) may be selected fortesting drilling fluids than for testing the solid formation itself. Forexample, to test the solid formation, a spectrometer may be configuredto use mid-infrared radiation (e.g., wavelengths from about 2.5 μm toabout 25.0 μm). Techniques for using infrared spectroscopy to measurethe properties of minerals are described in, for example, A. S.Povarennykh, “The Use of Infrared Spectra for the Determination ofMinerals,” 63 AMERICAN MINERALOGIST, 956-959 (1978); and Graham R. Hunt& John W. Salisbury, “Visible and Near-Infrared Spectra of Minerals andRocks: I Silicate Minerals,” 1 MODERN GEOLOGY 283-300 (1970), each ofwhich are incorporated in their entirety by this reference.

Raman spectroscopy may also be used to identify minerals. Spectra can begenerated for materials encountered in forming wellbores. Peaks appearhaving different Raman shifts, depending on the material. Therefore, amaterial may be differentiated from other materials by its Ramanspectrum. When drilling multiple wells in a field, the types of mineralsin the formation of the field may be identified in earlier-drilledwells, such that in subsequent drilling operations, an operator or acomputer may identify the same minerals. Thus, drilling conditions maybe varied in response to the in-situ identification of minerals.Techniques for using Raman spectroscopy to measure the properties ofminerals are described in, for example, Alian Wang et al., “RamanSpectroscopy as a Method for Mineral Identification on Lunar RoboticExploration Missions,” 100 J. GEOPHYSICAL RESEARCH 21189-99 (1995);Julie D. Stopar et al., “Raman Efficiencies of Natural Rocks andMinerals: Performance of a Remote Raman System for Planetary Explorationat a Distance of 10 Meters,” 61 Spectrochimica Acta Part A: Molecularand Biomolecular Spectroscopy 2315-2323 (2005); the entire contents ofeach of which are incorporated in their entirety by this reference.

Acoustic impedance may also be used to identify minerals. FIG. 5 is asimplified schematic of the cutting element 160″ of FIG. 4 in contactwith a formation 190. Acoustic (sound) waves are generated in theacoustic transceiver 180. The acoustic waves are transmitted through thecutting element 160″ to an interface between the cutting element 160″and the formation 190, then back through the cutting element 160″ to theacoustic transceiver 180. The fraction of reflected acoustic energydepends on the ratio of the characteristic (acoustic) impedance of thecutting element 160″ to the characteristic impedance of the formation190. Characteristic impedance is an intensive material property, and isdefined as the density of the material times the speed of sound throughthe material. The characteristic impedance of the cutting element 160″can be characterized in a laboratory to determine its changes withtemperature and pressure. Thus, the characteristic impedance of theformation material can be calculated based on the ratio of thetransmitted waves to the ratio of the reflected waves. Because differentminerals have different characteristic impedances, likely mineralogy canbe inferred. Techniques for using characteristic impedance to measurethe properties of minerals are described in, for example, MatthewSalisbury and David Snyder, “Application of Seismic Methods to MineralExploration,” in W. D. Goodfellow, ed., MINERAL DEPOSITS OF CANADA: ASYNTHESIS OF MAJOR DEPOSIT-TYPES, DISTRICT METALLOGENY, THE EVOLUTION OFGEOLOGICAL PROVINCES, AND EXPLORATION METHODS, 971-982 (GeologicalAssoc. of Canada, 2007); and Per Avseth et al., QUANTITATIVE SEISMICINTERPRETATION: APPLYING ROCK PHYSICS TOOLS TO REDUCE INTERPRETATIONRISK 168-211 (2005), each of which are incorporated in their entiretiesby this reference.

FIG. 6 is a simplified chart illustrating a signal 200 transmitted froman acoustic transceiver 180 (FIG. 5) and a signal 202 reflected from aninterface between the cutting element 160″ and the formation 190. Inuse, the cutting element 160″ may be kept in intimate contact with theformation 190 to provide a continuous medium through which the signals200, 202 can travel. The signal 202 has a lower amplitude than thesignal 200, and is determined by the ratio of the acoustic impedance ofthe cutting element 160″ to the acoustic impedance of the formation 190.Furthermore, there is a time delay Δt between transmission of the signal200 and reception of the signal 200 at the acoustic transceiver 180. Thetime delay Δt, which may be referred to in the art as “time of flight,”correlates with the distance the signals 200, 202 travel. Because thesignals 200, 202 travel through the cutting element 160″ and back, thethickness of the cutting element 160″ may be determined by the time offlight. Cutting elements 160″ tend to wear during use, so the thicknessof the cutting element 160″ may be used as an indicator of the conditionof the cutting element 160″.

Additional non-limiting example embodiments of the disclosure aredescribed below.

Embodiment 1

An earth-boring tool comprising at least one cutting element comprisinga hard material and at least one of a signal generator configured toprovide an electromagnetic or acoustic signal to an interface between asurface of the hard material and a subterranean formation in contactwith at least a portion of the surface, and wherein a sensor isconfigured to receive a return electromagnetic or acoustic signal fromthe interface.

Embodiment 2

The earth-boring tool of Embodiment 1, wherein the earth-boring toolcomprises a sensor configured as a spectrometer.

Embodiment 3

The earth-boring tool of Embodiment 2, wherein the spectrometercomprises an infrared spectrometer.

Embodiment 4

The earth-boring tool of Embodiment 3, wherein the spectrometercomprises a middle-infrared spectrometer.

Embodiment 5

The earth-boring tool of Embodiment 3 or Embodiment 4, wherein thespectrometer comprises a spectrometer configured to detect at least onewavelength from about 2.5 μm to about 12.0 μm.

Embodiment 6

The earth-boring tool of Embodiment 2, wherein the spectrometercomprises a Raman spectrometer.

Embodiment 7

The earth-boring tool of Embodiment 1, wherein the at least one of asignal generator and a sensor comprises an acoustic transducer.

Embodiment 8

The earth-boring tool of any of Embodiments 1 through 7, wherein the atleast one cutting element comprises a body having at least one exteriorsurface transparent to at least one wavelength of electromagneticradiation, the body defining at least one cavity therein.

Embodiment 9

The earth-boring tool of any of Embodiments 1 through 8, wherein the atleast one cutting element comprises diamond.

Embodiment 10

The earth-boring tool of Embodiment 9, wherein the at least one cuttingelement comprises a single-crystal diamond window.

Embodiment 11

The earth-boring tool of Embodiment 9, wherein the at least one cuttingelement comprises polycrystalline diamond.

Embodiment 12

The earth-boring tool of Embodiment 9, wherein the at least one cuttingelement comprises at least one diamond fiber configured to transmit theelectromagnetic or acoustic signal between the at least one of a signalgenerator and a sensor and the interface.

Embodiment 13

The earth-boring tool of Embodiment 9 or Embodiment 12, wherein the atleast one cutting element comprises at least one diamond fiberconfigured to transmit the electromagnetic or acoustic signal betweenthe interface and the at least one of a signal generator and a sensor.

Embodiment 14

The earth-boring tool of any of Embodiments 1 through 13, wherein theearth-boring tool comprises a transceiver comprising both a signalgenerator and a sensor.

Embodiment 15

The earth-boring tool of any of Embodiments 1 through 14, furthercomprising a module configured to transmit data between the sensor and adata collection system.

Embodiment 16

The earth-boring tool of any of Embodiments 1 through 15, furthercomprising at least one non-instrumented cutting element.

Embodiment 17

A method of forming a wellbore comprising rotating an earth-boring toolwithin a wellbore and cutting formation material with at least onecutting element mounted thereto, transmitting a signal through at leastone cutting element to an interface between a surface of the at leastone cutting element and the formation material, and measuring a responsereceived at a sensor from the interface as the at least one cuttingelement is used to cut formation material. The at least one cuttingelement comprises a generally planar volume of hard material. Theearth-boring tool further comprises a transmitter coupled to the atleast one cutting element, the transmitter comprising at least one of anelectromagnetic and an acoustic transmitter, and a sensor coupled to theat least one cutting element. The sensor is at least one of aspectrometer and an acoustic receiver, the signal is at least one of anelectromagnetic signal and an acoustic signal, and the response is atleast one of an electromagnetic and an acoustic response.

Embodiment 18

The method of Embodiment 17, wherein measuring a response received atthe sensor as the at least one cutting element is used to cut formationmaterial comprises determining a composition of the formation material.

Embodiment 19

The method of Embodiment 17 or Embodiment 18, wherein measuring aresponse received at the sensor as the at least one cutting element isused to cut formation material comprises determining a thickness of theat least one cutting element.

Embodiment 20

The method of any of Embodiments 17 through 19, wherein measuring aresponse received at the sensor as the at least one cutting element isused to cut formation material comprises measuring an amplitude of theresponse.

Embodiment 21

The method of any of Embodiments 17 through 20, wherein measuring aresponse received at the sensor as the at least one cutting element isused to cut formation material comprises measuring a period of timebetween the transmission of the signal and reception of the response atthe sensor.

Embodiment 22

The method of any of Embodiments 17 through 22, wherein measuring aresponse received at the sensor as the at least one cutting element isused to cut formation material comprises measuring an infrared or Ramansignal at the sensor.

Embodiment 23

The method of any of Embodiments 17 through 22, wherein measuring aresponse received at the sensor as the at least one cutting element isused to cut formation material comprises measuring a wavelength betweenabout 2.5 μm and about 12.0 μm.

Embodiment 24

The method of any of Embodiments 17 through 22, wherein measuring aresponse received at the sensor as the at least one cutting element isused to cut formation material comprises measuring an acoustic impedanceof the formation material.

Embodiment 25

The method of any of Embodiments 17 through 24, wherein rotating anearth-boring tool within a wellbore and cutting formation material usingthe cutting element comprises disposing the generally planar volume ofhard material parallel to and in contact with a surface of the formationmaterial.

Embodiment 26

The method of any of Embodiments 17 through 25, further comprisingrecording information received by the sensor.

Embodiment 27

The method of any of Embodiments 17 through 26, further comprisingcharacterizing a mineralogy of the formation material using dataobtained by the sensor.

Embodiment 28

A cutting element for an earth-boring drilling tool comprising a cuttingelement body having a cutting surface thereon, at least one transmitteroriented and configured to dispense an electromagnetic or acousticsignal to an interface between the cutting surface and a surface of asubterranean formation engaged by at least a portion of the cuttingsurface, and at least one sensor oriented and configured to measure asignal returned from the interface between the cutting surface and thesurface of the subterranean formation engaged by the at least a portionof the cutting surface.

Embodiment 29

The cutting element of Embodiment 28, wherein the at least one sensor isconfigured to measure an electromagnetic or acoustic signal reflectedfrom the interface.

Embodiment 30

The cutting element of Embodiment 28, wherein the at least one sensor isconfigured to measure an electromagnetic or acoustic signalretransmitted from the interface.

Embodiment 31

The cutting element of any of Embodiments 28 through 30, wherein the atleast one sensor is disposed within a void defined by the cuttingelement body.

While the present disclosure has been set forth herein with respect tocertain embodiments, those of ordinary skill in the art will recognizeand appreciate that it is not so limited. Rather, many additions,deletions, and modifications to the embodiments described herein may bemade without departing from the scope of the invention as hereinafterclaimed. In addition, features from one embodiment may be combined withfeatures of another embodiment while still being encompassed within thescope of the invention as contemplated by the inventors.

What is claimed is:
 1. An earth-boring tool, comprising: at least onecutting element comprising a hard material; at least one of a signalgenerator and a sensor; and at least one diamond fiber extending fromthe at least one of the signal generator and the sensor, through thehard material of the at least one cutting element, and to an interfacebetween a surface of the hard material and a subterranean formation incontact with at least a portion of the surface, wherein the signalgenerator is configured to provide an acoustic signal at least partiallythrough the at least one diamond fiber to the interface, and wherein thesensor is configured to receive a return acoustic signal from theinterface.
 2. The earth-boring tool of claim 1, wherein the at least oneof a signal generator and a sensor comprises an acoustic transducer. 3.The earth-boring tool of claim 1, wherein the earth-boring toolcomprises a transceiver comprising both a signal generator and a sensor.4. The earth-boring tool of claim 1, wherein the at least one of asignal generator and a sensor is configured to generate or detect anacoustic wave having a frequency between 15 Hz and 1 GHz.
 5. Theearth-boring tool of claim 1, wherein the at least one of a signalgenerator and a sensor is configured to generate or detect an acousticwave having a frequency between 50 kHz and 100 MHz.
 6. The earth-boringtool of claim 1, further comprising a bit body, wherein the at least onecutting element is secured to the bit body.
 7. The earth-boring tool ofclaim 6, wherein the bit body comprises at least one blade, and whereinthe at least one cutting element is secured to the at least one blade.